The present invention relates to forming laps from fibrous webs in general, and more particularly to a method of and an apparatus for forming wadding laps from wadding webs.
In the process of handling fibrous materials, for instance, prior to spinning, it is often necessary to form laps from webs of such fibrous material. Then, such laps may be used as the feed material for a ribbon lap machine and a subsequent combing process and apparatus.
In the formation of laps, two essential aims are, on the one hand, the achievement of a high specific weight of the material of the lap and, on the other hand, problem-free subsequent unrolling of the lap, that is, the avoidance of mutual entaglement of the fibers from any two adjacent or superimposed layers of the lap. In order to achieve these objectives, it has been previously proposed to subject the webs to so-called calendering prior to the formation of the laps from such webs. During such calendering operation, the advancing web is continuously pressed two or three times between calendering rollers and is drawn to a slight degree, so that condensing or compaction of the material of the web takes place.
In conventional arrangements utilizing this principle, the web either rests freely on one of two winding rollers between the last or downstream pair of calendering rollers and the lap-forming location, that is, the location at which the web first contacts the tube forming the core of the lap or the previous lap layer, or hangs freely between the last calender roller pair and the lap-forming location, that is, it is suspended unsupported in the air or, in other words, it is held only in the nip of the last calender roller pair and in the nip between the outer layer of the lap and the upstream winding roller. This brings about a substantial disadvantage, in that the web material "breathes" subsequent to the calendering operation, so that the thickness of the web again increases with respect to that at which the web leaves the nip between the last calendering roller pair. Thus, the material of the lap will have a reduced specific density. Also, experience has shown that the fibers of the superimposed layers of the lap may become entangled with one another, which creates problems during the unwinding of the lap.